The concept of multiplexing packet data flows, including real-time transport protocol (RTP) flows together into a single aggregate flow is a concept that is addressed in a number of Internet engineering task force (IETF) Internet drafts. Multiplexing RTP flows would be desirable, because it can reduce the bandwidth usage of wide area network (WAN) links and decrease the RTP packet rate incident on edge routers. In addition, the multiplexing of RTP flows reduces the burden of administering networks, for example in connection with the configuration of quality of service levels. In addition, multiplexing RTP flows can increase the scalability of existing quality of service schemes.
Although IETF Internet drafts specifying packet formats for aggregate flows, header compression algorithms, and packet loss compensation have been proposed, there are no methods for discovering the RTP multiplexing capabilities of a remote subnetwork. Discovery of such capabilities is desirable in order to determine whether packet data flows addressed to devices on a particular subnetwork are suitable for aggregation.